Preheat your oven to 375°F (190°C).
In a large saucepan, melt the butter over medium heat.
Add the minced garlic and shallot and sauté for 1-2 minutes until fragrant.
Add in ricotta and stir until fully mixed.
Gradually pour in the milk, whisking continuously to avoid lumps.
Allow the mixture to simmer and thicken, about 5-7 minutes.
Stir in the Parmesan cheese, Italian seasoning or fresh herbs, salt, and black pepper. Remove from heat and set aside.
Prepare the ricotta mixture by combining ricotta, cooked spinach, egg, shredded mozzarella, Italian seasoning, salt and pepper and stir to combine.
Spread a thin layer of white sauce on the bottom of a 9x13-inch baking dish.
Lay down 3 lasagna noodles in a single layer.
Spread chicken over the noodles
Spread the ricotta mixture
Spread the white sauce and repeat the layers!
For the final layer, top with fresh mozzarella (optional)
Step 4: Bake the Lasagna
Cover the baking dish with aluminum foil to prevent the cheese from over-browning.
Bake for 25 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is golden and bubbling.
Let the lasagna rest for 10-15 minutes before slicing to allow it to set.